Device and a method for melting snow and ice of a railway

ABSTRACT

A device for heating of railway tracks is provided. The device comprises a magnetic field generator fed with a low-frequency current. The magnetic field generator is formed by a device without a circuit returning a magnetic flux generated by the magnetic field generator. Hereby the magnetic flux can be returned via a heater. The heater is a material generating heat when placed in the magnetic field. The heater can be the railway tracks or a plate provided in conjunction with the railway tracks.

TECHNICAL FIELD

The present invention relates to devices for removing snow and ice fromrailway tracks and in particular from rail road switches.

BACKGROUND

In winter climates, there is a high demand to keep railway tracks freefrom snow and ice. The methods and devices used for removing the snowand ice range from manually removal to thawing and heating devices ofdifferent types.

For example, U.S. Pat. No. 6,664,521 describes an inductive snow meltingdevice. The device in U.S. Pat. No. 6,664,521 removes snow by heating afloor plate using a heating coil that is fed with a high frequencycurrent.

Today, there is a trend toward a higher use of railways fortransportation of goods and people. This has led to a higher utilizationof railways. This in turn has resulted in that the maximum capacity ofrailroads now has been reached or almost reached in many places. Therailway must hence be constantly available and there is little or notime to manually remove ice or snow from the tracks or thaw them withconventional thawing devices.

Hence there exists a need for new devices providing improved performancein snow and ice removal from railway tracks.

SUMMARY

It is an object of the present invention to provide an improved methodsand devices to address the problems as outlined above.

This object and others are obtained by the methods and devices as setout in the appended claims.

As has been realized by the inventor, an inductive ice-melting and snowremoval device making use of a high-frequency input current such as thedevice described in U.S. Pat. No. 6,664,521 has great limitations. Forexample, the need for high frequency components in an environment inneed of ice-melting and snow removal is highly unsuitable and can causemalfunction in the system. The mean-time before failure (MTBF) will alsobe short.

Further, high frequency components are not desired because there will bea risk of interference with other electrical devices, in particularradio frequency devices.

The present invention solves the above problems in that an inductiveheating device fed with a low-frequency current is provided. Thus, bygenerating heat with an inductive heating device designed to operate onlow-frequency current a number of advantages can be achieved.

In accordance with embodiments described herein a device for heating ofrailway tracks is provided. The device comprises a magnetic fieldgenerator fed with a low-frequency current. The magnetic field generatoris formed by a device generating a magnetic flux without a circuitreturning the magnetic flux generated by the magnetic field generator.Instead the magnetic flux is closed via some other component here termeda heater. Hereby, the magnetic flux can generate heat in the heater. Theheater is a material generating heat when placed in the magnetic fieldfrom the magnetic field generator. The heater can be the railway tracksor a plate provided in conjunction with the railway tracks or some otherdevice generating heat when placed in a magnetic field.

The use of an inductive heating device fed with a low-frequency currentin accordance with some embodiments will thus provide numerousadvantages over existing devices for removing snow and ice from railwaytracks. The advantages include, but are not limited to an effective useof the applied power, heat generation in a well-defined area, a simpleand robust design with a high MTBF, and no high frequency radiofrequency interference.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by way ofnon-limiting examples and with reference to the accompanying drawing, inwhich:

FIG. 1 is a view of a railway track heating device,

FIGS. 2a -5 are views depicting some parts of a railway track heatingdevice,

FIG. 6 is a view of a railway track heating device,

FIG. 7 is a view of a heating device for removing snow and ice from arailway switch,

FIG. 8 is a view of a heater plat, and

FIGS. 9a-9c illustrate a heating device in accordance with anembodiment.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments ofthe invention are shown. The invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided byway of example so that this disclosure will be thorough and complete,and will fully convey the scope of the invention to those skilled in theart. Like numbers refer to like elements throughout the description.

In FIG. 1, a general view of an exemplary heating device 9 for heatingrailway tracks is depicted. The heating device 9 is provided for thepurpose of ice-melting and snow removal. This is also referred to asdefrosting.

The railway track heating device 9 in FIG. 1 is formed by a magneticfield generator 1 formed by an induction core having a coil. Themagnetic field generator 1 is operative to work in conjunction with aheat element 3 in which the magnetic field generated by the magneticfield generator is transformed into heat. The heat element 3 can be asection of the railway or some other metal portion having magnetic fluxproperties that are worse than the induction core. In particular, theheat element 3 can be combined with a heat spreader 2 as described belowto form a heater. Hereby, the magnetic flux generated by the magneticfield generator will heat the heat element 3.

As set out above, the heat element 3 can be supplemented by a heatspreader 2. The purpose of the heat spreader 2 is to spread the heatgenerated in the heat element 3 over a larger area thereby forming alarger heater in the overall device. The heat spreader 2 can be securedto the railway tracks by means of a securing device 4. In accordancewith one embodiment the railway track heating device 9 is secured to therailway tracks by the securing device 4. The securing device 4 can beclamped around the bottom section of the railway tracks and also beattached to the inductive core whereby the heating device can be held inplace. The magnetic field generator 1 is fed with a low frequency powervia a power cable 6. To control the heat generated by the device athermostat 5 can in accordance with some embodiments be provided that isoperative to turn the power supply off and on in response to the currenttemperature in the heat element or a device in thermal contact with theheat element 3.

In an alternative embodiment, the thermostat can be omitted by properdimensioning of the heat element 3. In FIG. 8, a plate 8 that can beused in a heater (a heat element or a heat spreader) is shown. The plate8 can be provided with holes. By selecting the dimensions of the plate(or any other element used as the heat element) a heater that isself-controlled in terms of temperature can be formed. Thus, when thetemperature rises in the plate as a result of the magnetic flux, themagnetic flux will decrease thereby acting against a continued risingtemperature. Hence, by proper selection of the material, dimensions, andgeometric layout of the plate acting as a heat element 3 can beself-regulating in terms of the heat it generates. In other words, thephysical properties will determine a particular temperature generated bya particular magnetic flux generator and the system formed by the heatelement and the magnetic flux generator will have a particulartemperature towards which the system will self-regulate towards a steadystate temperature. A number of different parameters can be adjusted toprovide a heat element 3 having the desired temperature characteristics,i.e. generate the desired temperature when placed in the magnetic flux.For example, one or more of the following parameters can be varied. Thelength, width, thickness of the heat element, the geometric shapeincluding provision of holes in the heat element, selection of materialand combination of materials in the heat element. In general, anyparameter changing the magnetic flux pattern through a heating elementcan be adjusted to have the heating element generate the desiredtemperature. Also, the heat spreader 2, acting as a supplement to theheat element 3, can be designed in accordance with the above to comprisea plate 8.

The magnetic field generator 1 can be formed by an arrangement having acoil driving a magnetic flux in an inductive core, but without a circuitreturning the magnetic flux. Instead the heating device, such as therailway tracks or a heat element, will serve as a return for themagnetic field generated by the magnetic field generator. The railwaytracks have poor properties for conducting a magnetic flux. As a result,the railway tracks will generate heat when placed as a return closingthe loop for the magnetic flux.

Some different parts of the device in FIG. 1 will now be described inmore detail with reference to FIGS. 2a -5.

In FIG. 2a , a coil 11 that can be fed with a low frequency current isdepicted in a top view. The coil can be formed by a material having goodelectrical conductive properties such as copper. The low frequencycurrent flowing through the coil 11 will cause the generation of amagnetic field. The frequency of the low-frequency current can beselected to any suitable value. However, the use of a current frequencyalready at hand where the magnetic field generator is to be deployed istypically advantageous. Hence, the coil can be fed with a current havinga frequency of 16, 50 or 60 Hz. In FIG. 2b the coil 11 is depicted fromthe side. Also, more than one coil can be used for generating themagnetic flux.

In FIG. 2c a top view of an inductive core 10 is depicted. In FIG. 2d aside view of the inductive core 10 is shown. The inductive core in FIGS.2c and 2d is generally E-shaped and can be formed by a material havinggood properties for a magnetic flux. The inductive core can be made fromtransformer plates. In another embodiment (not shown) the inductive corecan be generally U-shaped. Other forms of the inductive core arepossible. In general, the form of the core is such that a magnetic fluxflowing in the core will need to be closed via some other material thanthe core. Hence, the inductive core 10 will have a form without closedloops. Hereby, a coil around the inductive core fed with an alternatingcurrent will drive a flux in the inductive core and where the flux willneed to be closed outside the inductive core. This is generally referredto as a magnetic field generator herein.

In FIG. 2e , a top view of a magnetic field generator formed by a coil11 and an inductive core 10 is shown. The coil is located around themid-section of the generally E-shaped inductive core. When fed with alow frequency current, a magnetic flux will be generated inside theinductive core and on top of the inductive core. In FIG. 2f a top viewof a magnetic flied generator formed by a coil 11 and an inductive core10 is shown.

In FIG. 3a a cross sectional view of an exemplary heat spreader 2 isshown. The heat spreader 2 can be provided with a securing device 4.Also, the bottom of the railway tracks is shown. FIG. 3b is a lateralview of the heat spreader 2 and in FIG. 3c the heat spreader 2 is shownin a top view. The heat spreader 2 can be made from a plate of aluminumor some other material with poor properties for conduct magnetic flux orstated differently having good properties for generating heat whenplaced in a magnetic flux. The heat spreader 2 can be provided withholes or slits to increase the heating and to spread the heating betterover the plate.

In FIG. 4a , a cross sectional view of a heating device formed by themagnetic field generator 1 of FIG. 2f when combined with a heater thatcan be formed by a heat element 3 and a heat spreader 2 of FIG. 3a .Thus, the heater, generally denoted with reference numeral 13, is placedon top of the magnetic field generator formed by an inductive core 10and having at least one coil 11 for generating a magnetic flux. Becausethe arrangement formed by the inductive core and the at least one coilhas no circuitry for returning the magnetic flux on the top of themagnetic field generator, the magnetic field on top of the magneticfield generator will pass through the heater 13. The heater 13, whichcan be the railway tracks or a plate or some other suitable heatgenerating device such as the heat spreader 2, will return the flux tothe inductive core and thereby close the loop for the magnetic fluxgenerated by the at least one coil. The heater 13 can be optimized togenerate a maximum amount of heat from the magnetic flux flowing throughthe heater 13. The heater 13 can be secured tom the railway via securingdevices 4. To control the heat a thermostat 12 can be used. Thethermostat 12 can be provided to control the low frequency current powerfed to the coil 11. In FIG. 4b a lateral view of the heating device isshown. In FIG. 4c a top view of the heating device is shown.

In FIG. 5 another top view of the heating device is shown. In the topview of FIG. 5 the purpose of the holes or slits in the heater 13, inparticular the heat spreader 2, is illustrated. Thus, by providing holesor slits in the heat spreader 2 the magnetic field lines shown in FIG. 5are made to go around the holes or slits thereby spreading the magneticflux over a wider area, which turn spreads the heat better.

In FIG. 6, a railway switch 80 is depicted. The switch 80 is providedwith inductive heaters 100. The inductive heaters can for example be anyof the heating devices as described above. For example, the heater canbe a heater 13 as set out above. The heater 100 is heated used inductivearrangements 110. The inductive arrangements can be of the typedescribed above formed by an inductive core 10 in which a magnetic fluxis generated by at least one coil, and where the magnetic flux is madeto return via the heater 100. The heater can comprise a plate 8 of thetype described above which can be located between the sleepers 120 ofthe railway track. In particular, the heater can be located beneath thepoints of the railway switch. Hereby it is possible to keep the switchfree from snow and ice. In accordance with some embodiments, a plate 8is located in the space between a tongue and a support rail as is shownin FIG. 6. Hereby the area between the tongue and the support rail canbe freed from snow and ice whereby the working of the switch is improvedin snowy conditions.

In FIG. 7, a heating arrangement having a magnetic field generator inaccordance with the above is shown. The magnetic field generatorcomprises a coil that can drive a magnetic flux in the E-shaped core.The arrangement can be said to resemble a transformer arrangementwithout a circuit closing the magnetic flux. Hereby, a magnetic field 25is generated outside the core. The arrangement is used to heat railwaytracks 20. By providing a magnetic field generator in conjunction withrailway tracks an arrangement whereby the railway tracks can be heatedusing a magnetic field generated by the magnetic field generator. Themagnetic field is illustrated by magnetic field lines 25 in FIG. 7. Therails are hereby heated using induction. The magnetic field generator(the inductive core 10) will it self not be heated. Instead the magneticfield will generate heat in the metal forming the railway tracks.

In accordance with some embodiments one or more magnetic fieldgenerators are located between the sleepers of the railway track.Further, entire railway sections can be heated as one unit. Typically,the lateral heating is limited compared to vertical heating whereby theheating can be made local at locations where heating is deemed importantand or desired. For example, such locations can be railway switches,which can become stuck due to ice and snow.

As set out above, the magnetic field generator can be fed via a powersupply 30 with a suitable voltage and frequency. For example, thearrangement can be fed from an existing power supply. Thus, if only 16Hz is available at the location where the arrangement is to be deployed(because the railway is operated using 16 Hz power supply), thearrangement can be designed/dimensioned to operate at this frequency.Other suitable power frequencies can be 50 Hz and 60 Hz. The heatingpower generated by the arrangement can be dimensioned in accordance withthe heating demand. For example, the arrangement when used for a railwayswitch can be dimensioned to generate heating power in the range 10-500W, other heating powers are also envisaged such as in the range of 200 Wto 2000 W or even higher than 2000 W.

In accordance with some embodiments the magnetic field generator isconnected to a control unit. 40. The control unit is provided to controlthe power fed to the magnetic field generator so that a suitable heat isgenerated in the railway tracks. In accordance with one embodiment thecontrol unit is connected to a heat sensor 50 provided in conjunctionwith the railway tracks. The heat sensor can be a thermostat or anIR-sensor or some other suitable sensor. The power fed to the magneticfield generator is controlled by the control unit 40 in response to theoutput signal from the sensor 50 or other sensors or controllers. Thecontrol unit 40 can further be connected to other sensors generallydesignated by reference numeral 60 in FIG. 7 from which data can beforwarded to control the magnetic field generator. For example, inputcan be received about temperatures or whether forecast. The heat canthen be controlled based on forecast or outside temperature or othersuitable parameters to prevent ice and snow on the railway track.

In FIGS. 9a-9c another exemplary embodiment is depicted. FIG. 9a depictsthe device from the side in the direction of the rails. FIG. 9b is alateral view and FIG. 9c is a top view of the device described herein.The dimensions illustrated in mm in the figure are for illustrationpurposes and can be varied to meet specific implementation needs.Generally, the railway track heating device 9 can be made small andhaving a height of less than 100 mm when mounted under the surface of arailway.

1. A device for melting snow and ice of a railway, the device comprisinga magnetic field generator fed with a low-frequency current and adaptedto generate a magnetic flux, the device further comprising a heatelement located in the magnetic flux generated by the magnetic fieldgenerator generating heat when a magnetic flux goes through the heatelement.
 2. The device according to claim 1, wherein the temperature inthe heat element is controlled by a heating sensor.
 3. The deviceaccording to claim 2, wherein the heating sensor is a thermostat.
 4. Thedevice according to claim 1 wherein the frequency of the low-frequencycurrent is the same as the frequency of the current used by trainsrunning on the railway tracks.
 5. The device according to claim 4,wherein the low-frequency current is 16, 50 or 60 Hertz.
 6. The deviceaccording to claim 1 wherein the magnetic field generator comprises acore and at least one coil generating a magnetic flux in the core whenfed with the low frequency current.
 7. The device according to claim 6wherein the core of the magnetic field generator is generally E shaped.8. The device according to claim 1, wherein the temperature of the heatelement is controlled by the physical properties of the heat element. 9.The device according to claim 6, wherein a plate is provided and theplate forms at least a part of the heat element.
 10. The deviceaccording to claim 9, wherein the plate is located under the railwaytracks.
 11. The device according to claim 10, wherein the plate islocated between the sleepers of the railway tracks.
 12. The deviceaccording to claim 9, wherein the plate is located under the switchpoints of a railway switch.
 13. The device according to claim 9, whereinthe plate is made of aluminum.
 14. The device according to claim 9,wherein the plate is provided with holes and or slits.
 15. The deviceaccording to claim 9, wherein the plate is located in an area between atongue and a support rail.
 16. A method for melting snow and ice of arailway, the method comprising feeding a magnetic field generator with alow-frequency current, and generating a magnetic flux, the magnetic fluxpassing through a heat element located under the railway tracks andthereby generating heat in the heat element wherein the temperature ofthe heat element is controlled by selection of the heat element.
 17. Themethod according to claim 16, wherein the temperature is selected byselecting one or more of the following parameters of the heat element:the length, width, thickness of the heat element, the geometric shapeincluding provision of holes or slits in the heat element, selection ofmaterial and combination of materials in the heat element.
 18. Themethod according to claim 16, wherein the heat element is formed as aplate.